function GuiTableRowPurchase() {
};

GuiTableRowPurchase.instance = function(prefix) {
  return { name: document.getElementById(prefix + '_name_td'),
           qty: document.getElementById(prefix + '_quantity_td'),
           unit: document.getElementById(prefix + '_unit_td'),
           price: document.getElementById(prefix + '_price_td'),
           remove: document.getElementById(prefix + '_remove_td')
         };
};